Alpha process for refining petroleum oils



Patented Nov. 22, 1932 seas FRANK WILLET HEATH, OF PITTSBURG, CALIFORNIA, ASSIGNOR TO SHELL DEVELOP- MENT COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELAWARE A PROCESS FOR REFINING PETROLEUM OILS No Drawing.

This invention relates to the purification of hydrocarbons, and while not necessarily confined thereto, it more specifically refers to the treatment of naphtha or gasoline stock synthetically produced. by the cracking of hydrocarbon oils, such as petroleum or shale oil, or distillates derived from relatively high sulfur-bearing crude oils in which hydrogen sulfide, mercaptans and other sulfur-bearing hydrocarbons, as well as varying percentages of unstable hydrocarbons, such as diolefines, may be present, or formed during said distillation or cracking process.

The invention is concerned with an oxidation refining process that will improve light petroleum oils particularly in the direction of stability against decomposition b long time storage, sunlight or storage at e evated temperatures, thereby promoting stability of color.

The invention further relates to a process wherein the oxidant employed also acts as a sweetening agent.

More specifically, one of the principal objects of this invention is to simultaneously oxidize and polymerize undesirable constituents of light petroleum oil at normal temperature and pressure, thus rendering them soluble in a suitable solvent, the latter effecting removal of the altered constituents by solution and separation and chemical reactions. I

It is customary to employ sulfuric acid as a refining agent for petroleum oils. A secondary stage in refining is usually resorted to in order to clear up the so-called sour condition of light oils. This secondary refinement is usually carried on by the use of sodium or calcium plumbite, with or without sulfur, copper hydroxide, sodium hypochlorite and similar reagents. Usually this secondary refining stage leaves the light oils in a condition in which they are much less stable towards the action of sunlight than they were after their distillation following the sulfuric acid treatment.

By simultaneously oxidizing and polymerizing the undesirable constituents of the light petroleum stock, rendering them soluble in 0 a solvent so that they may be removed by a Application filed October 22, 1930. Serial No. 490,549.

subsequent treatment with the latter reagent, it is not necessary to follow the sulfuric acid treatment with the common type sweetening agent after distillation as all the mercaptans and hydrogen sulfide as well as the compounds which later oxidize to form gums and cause instability of color are converted into compounds soluble in a common solvent. Upon subsequent distillation, the distillate is found to be color stable to the action of sunlight, deposits no gum and no mineral acidity is developed.

This is in accordance with my theory that any treatment of gasoline to produce light and storage stable products must remove phenols and other compounds which upon oxidation are converted into colored substances, either by converting them into these colored substances and then removing the latter or else destroying the oxidizable compounds before forming the colored substances. I have found it preferable to employ the first method.

The principal cause of color instability is the development of mineral acidity. The sulfur compounds are responsible for this reaction, particularly those that decompose with the liberation of sulfur dioxide.

I have found that alkaline potassium ferricyanide causes the removal or transforma- (and which if permitted to remain in the oil,

as is the present practice, would oxidize by absorption of oxygen from theair and cause a discoloration of the distillate) into colored compounds which are soluble in sulfuric acid and distillation.

and may be removed by treatment with this rea ent.

he alkaline potassium ferricyanide oxidizes hydroxy phenyl compounds to quinones and other coloring compounds such as: resins, conjugated phenols and possibly some polyhydroxy compounds which are also responsible for the discoloration of gasoline. These compounds are soluble in sulfuric acid as are the oxidation products of the sulfur compounds.

Thus, in a single stage, I can convert deleterious substances, dissolved in gasoline, to products which can be easily removed by a common acid solvent, producing a colorstable and sweetened gasoline.

The following example is cited only for purposes of illustration.

Pressure distillate is treated with H SQ.

" (83% strength), washed with water, treated with 10% by volume of NaOI-I (8 B.) and washed with water. The treatments so far are more or less customary. Then 15% by volume of ferricyanide solution is added to the pressure distillate and agitated therewith. The solution is composed of w G rams H2O 2, 000 NaOH 30o xsrqou). 300

Strong sulfuric acid is used to remove the dye and sulfonic acids formed and separation is preferably followed by neutralization The distillate is sweet to the doctortest, stable to the action of sunlight and storage and does not form H 'S or mercaptans upon its hydrogenation with zinc and hydrochloric acid. 7

The pressure distillate may be added to the potassium ferricyanide solution or vice versa so long as vigorous agitation is maintained between the two to promote intimate contact. I

Any alkali metal ferricyanide may be employed in lieu of the potassium salt.

Although sulfuric acid is -specifically mentioned as a commonsolvent for the conversion productsof sulfur and chromogenic compounds, other suitable solvents, such as phosphoric acid (approximately 85% by weight) concentrated I-ICl, concentrated HNO concentrated H 80 OI-LOI-I, alcoholic KOI-I, aniline, etc., may be employed without departing from the spirit of my in- While I in some detail a preferred method of operating my invention andsome variants thereof, it will be understood that this is only for the purpose of making the invention more have in the foregoing described clear and that the invention is not to be regarded as limited to the details of operation described, nor is it dependent upon the soundness or accuracy of the theories which I have advanced as to the reasons for the advantageous results attained. On the other hand, the invention is to be regarded as limited only by the terms of the accompanying claims, inwhich it is my intention to claim all novelty inherent therein as broadly as is possible in view of the prior art.

I claim as my invention:

1. A process for obtaining color-stable and doctor-sweet gasoline from light mineral oil distillates comprising simultaneously oxidizing and polymerizing all the undesirable constituents, which normally tend to formsour oil distillates by the addition thereto of an alkali-metal ferricya nide and extracting said oxidized and polymerized bodies with an acid solvent.

8. A process for obtaining colorstable, and I doctor-sweet gasoline from light mineral oil I distillates comprising causing instantaneous discoloration of the light mineral oil distillates by means of the chromogenic bodies contained therein by the addition thereto of an alkali-metal ferricyanide and extracting :1 f v the colored products formed with an acid.

4:. A process for obtaining color-stable and distillates comprising simultaneously oxidizdoctor-sweet gasoline from light mineral oil ing and polymerizing all the undesirable constituents, which normally tend to form sour and colored products, in the light mineral oil distillates by the addition thereto of an alkali-metal ferricyanide and extracting said oxidized and polymerized bodies with sulfuric acid.

5. A process for obtaining color-stable and. doctor-sweet gasoline from light mineral oil distillates comprising intimately contacting a solution of an alkali-metal ferricyanide 120.

with a light mineral oil distillate and extracting the colored-products and sulfur compounds formed with anacid solvent.

6. A process for obtaining'color-stable and doctor-sweet gasoline fromlightmineral oi 1 distillates comprising intimately contacting.

a solution of an alkali-metal ferricyanide with alight mineral oil distillate and extract;

ing the colored products and sulfur compounds formed with sulfuric acid.

7. A process for obtainingcolor-stable and doctor-sweet gasoline from light mineral oil distillates comprising intimately contacting a solution of potassium ferricyanide with a light mineral oil distillate and extracting the colored products and sulfur compounds formed with an acid solvent.

8. A process for obtaining color-stable and doctor-sweet gasoline from light mineral oil distillates comprising intimately contacting a solution of potassium ferricyanide with a light mineral oil distillate and extracting the colored products and sulfur compounds formed with sulfuric acid.

9. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillate comprising simultaneously oxidizing and polymerizing all the undesirable constituents, which normally tend to form sour and colored products, in the cracked distillate by the addition thereto of an alkali-metal ferricyanide, extracting said oxidized and polymerized bodies with a solvent, neutralizing the liquid mixture and distilling.

10. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillate comprising simultaneously oxidizing and polymerizing all the undesirable constituents, which normally tend to form sour and colored products, in the cracked distill-. ate by the addition thereto of an alkalimetal ferricyanide, extracting said oxidized and polymerized bodies with an acid solvent, neutralizing the liquid mixture and distilling.

11. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillates comprising simultaneously oxidizing and polymerizing all the undesirable constituents, which normally tend to form sour and colored products, in the cracked distillate by the addition thereto of an alkali-metal ferricyanide, extracting them with sulfuric acid, neutralizing the liquid mixture and distilling.

12. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillates comprising intimately contacting a solution of an alkali-metal ferricyanide with a cracked distillate, extracting the colored products and sulfur compounds formed with an acid solvent, neutralizing the liquid mixture and distilling.

13. A process for obtaining color-stable and doctor-sweet gasoline from cracked dis tillate comprising intimately contacting a solution of an alkali-metal ferricyanide with a cracked distillate, extracting the colored products and sulfur compounds formed with sulfuric acid, neutralizing the liquid mixture and distilling.

14. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillates comprising intimately contacting a solution of potassium ferricyanide with a cracked distillate. extracting the colored products and sulfur compounds formed with an acid solvent, neutralizing the liquid mixture and distilling.

15. A process for obtaining color-stable and doctor-sweet gasoline from cracked distillates comprising intimately contacting a solution of potassium ferricyanide with a cracked distillate, extracting the colored products and sulfur compounds formed with sulfuric acid, neutralizing the liquid mixture and distilling.

In testimony whereof, I have hereunto set my hand.

FRANK WILLET HEATH. 

